1. Field of the Invention
The invention comprises processes for the formation of ultrafine metal powders by forming solid solutions with stable metals. More specifically, the present invention is directed to of non-pyrophoric submicron magnetic alloy powders from Group VIII metals. Such metals have varied utility in the fields of: catalysis, communications, electrical contacts, magnetics, electron emission and related circuitry, alloying and brazing, reduction, hydrogenation, chemical catalysis, ignition and the like. Submicron or ultrafine alloy powders are herein defined as having specific surface areas greater than one square meter per gram and equivalent spherical diameter of less than one micron.
2. Prior Art
In finally divided forms, many metal powders become highly reactive, especially, toward our oxygen-containing atmosphere. For example, ultrafine iron powder is pyrophoric and many Raney nickel catalysts ignite spontaneously when dried and exposed to the atmosphere. Aluminum metal pigments may explode if subjected to a spark or flame. Accordingly, it is very desirable to create ultrafine metal powders which may be handled without concern for the likelihood of spontaneous ignition or combustion. It is known that one way to increase the stability of a metal toward oxidation is through alloying; nontheless, the alloying does not permit the production of submicron alloy powders. Some metals such as platinum and gold can be produced in finely divided form without being pyrophoric, however their very high cost severely limits practical applications.
Examples of prior art relating to stabilization of metals and to fine metal represented in the powders are the following United States Letters Patent:
U.S. Pat. No. 4,485,153 dated Nov. 27, 1984--Conductive Pigment--Coated Surfaces--Inventor Daniel S. Janikowski.
U.S. Pat. No. 4,447,391 dated May 8, 1984--Brazing Alloy Containing the Active Metals, Precious metals, Boron and Nickel--Inventor Howard Mizuhara.
U.S. Pat. No. 4,081,710 dated Mar. 28, 1978--Platinum--Coated Igniters--Inventors Alane E. Haywood, et al.
U.S. Pat. No. 3,348,770 dated Apr. 15, 1969--Brazing Alloy of Improved Workability Containing Nickel and Palladium--Inventor Charles A. Clark, et al.
U.S. Pat. No. 3,882,050 dated May 6, 1975--Method of Depositing A Noble Metal on a Surface of a Nickel Support.
U.S. Pat. No. 3,032,515 dated May 1, 1962--Method of Preparation and Stabilization of Catalysts--Inventor Orville N. Hinsgar.
U.S. Pat. No. 2,977,327 dated Mar. 28, 1961--Process of Producing Nickel Catalysts--Inventor Murray Raney.
U.S. Pat. No. 2,269,497--Nickel--Platinum Alloy--Inventor Michael B. Vilensky.
U.S. Pat. No. 1,832,307--Alloy for Electrical Contracts--Inventor Edwin F. Kingsbury.
French Pat. No. 2,530,160 Nat'l No. 8311790--Catalyseur etc.